Field of the Invention
The invention relates to an apparatus for power failure identification in a household appliance. The appliance is supplied through a mains switch from an electrical power supply system, is programmable and can be switched off by an operator deliberately even while the program is running. The appliance has an electronic program control apparatus and an electronic memory for recording the program status, in which, if the power supply system fails, the program status that has been reached can be stored. In which case it is possible to decide in the program control apparatus whether the failure of the electrical variable of the household appliance is due to a failure of the power supply system or due to the household appliance being switched off deliberately, and in which case once the failure of the power supply system has ended, the program control apparatus can cause the running of the program to be continued from the program status that has been reached.
An apparatus is disclosed from European Patent Application EP 0 027 432 A2, and describes a circuit by which data that relates to an operating program in a household appliance, in particular, a washing machine, can be stored in digital form in an electronic data memory. A program control apparatus is integrated in the household appliance, which ensures that the program data is stored in the memory at specific time intervals while the operating program is running. The program control apparatus calls the data when the supply voltage is restored after an intentional or random interruption in it.
The prior art household appliance has an on/off switch through which the appliance is connected to the electrical power supply system. The program control apparatus receives input signals and produces output signals. It is also connected to an electronic memory, in which data can still be stored in digital form even in the event of a power failure. Storage is possible because a battery is provided in the household appliance, by which the program control unit and the data memory can be supplied with power in the event of a power failure. When the mains voltage is restored after a power failure, the program control apparatus restarts the program counter at a zero value after a reset cycle and then, provided the data stored in the memory is correct, continues the operating program that is to be run from approximately the point where it had been interrupted. However, if the operator switched off the household appliance, no standby voltage supply is provided by the battery once the voltage has been switched off, so that the memory loses its data.
It is accordingly an object of the invention to provide an apparatus for power failure identification in a programmable household appliance that overcomes the hereinafore-mentioned disadvantages of the heretofore-known devices and methods of this general type and that reduces the circuit complexity within the household appliance as compared to prior art household appliances.
With the foregoing and other objects in view, in a programmable household appliance configured to be switched off by an operator deliberately even while a program is running there is provided, in accordance with the invention, a power failure identification apparatus including a power supply, a mains switch supplying power to the appliance from an external electrical power supply system, the mains switch electrically connected to the power supply, an electronic program control apparatus electrically connected to the power supply and to the mains switch, the control apparatus having a memory for recording a program status of the appliance, a first identification device disposed between the mains switch and the external power supply system, a second identification device disposed between the mains switch and the appliance, the first and second identification devices each identifying an electrical variable of at least one of the external power supply system and the power supply, and producing an output signal based upon the electrical variable and the control apparatus programmed to store the program status if the external power supply system fails, to compare the output signal of each of the first and second identification devices, to determine whether one of a failure and a change in a respective electrical variable is due to a failure of the external power supply system or to the operator deliberately switching off the appliance, and to continue running the program from a point defined by the program status once the failure of the external power supply system has ended.
According to the invention, a first identification device, which is upstream of the mains switch on the side of the power supply system, and a second identification device, which is downstream from the mains switch on the appliance side, are provided to identify an electrical variable of the power supply system or of the supply system in the household appliance, and in that it is possible to decide, by a comparison of the signals produced by each of the devices from the electrical variables, in the program control apparatus whether the failure or the change in the electrical variable of the household appliance is due to a failure of the power supply system or to the household appliance being switched off deliberately.
These identification devices make it possible to distinguish between the return of the power supply system after a random power failure and the system being switched on again by the mains switch after having previously been switched off deliberately by the mains switch. The decision feature in this case is that the mains voltage is still present upstream of the mains switch in the second case. It is, therefore, necessary to check both for the presence of the mains voltage directly at the mains connection of the household appliance, that is to say, upstream of the mains switch, and downstream from it. These measurement variables are detected and evaluated in a part of the program control apparatus. Thus, the invention provides a solution, which is less costly than the prior art, saves more space, and does not require a complex switching mechanism.
It is self-evident that the expression identification device or means for identifying an electrical variable also, for the purposes of the invention, covers an identification device or means for identifying a magnetic field that is produced as a result of an electric current flowing.
In accordance with another feature of the invention, the identification device on the power supply system side for identifying the supply voltage are isolated, that is to say conductively isolated, from the potential of the mains voltage. By way of example, a circuit having at least one optocoupler is provided, with this circuit having at least one transmitting diode on the input side and at least one receiving diode or phototransistor on the output side. Its signal is then amplified and is supplied to the program control unit.
Electrical circuits for household appliances that use water and that have a door-operated switch are disclosed in U.S. Pat. No. 5,202,582 to Szynal et al. and U.S. Pat. No. 4,241,400 to Kiefer. All the electrical loads are switched off when the door is opened.
In accordance with a further feature of the invention, the current through the transmitting diode of the optocoupler is preferably limited by a power supply system capacitor or a power series resistor. A capacitor of a radio suppression filter is also suitable for use as a power supply system capacitor. A relay or a transformer can also be used, as an alternative to the use of an optocoupler. The output signal from the receiving diode or from the phototransistor is digitized by a level converter, preferably, a Schmitt trigger.
In accordance with an added feature of the invention, the voltage from the device identifying the presence of a voltage within the appliance is preferably the voltage produced by a power supply unit within the appliance.
In accordance with an additional feature of the invention, program control apparatus contains a microcontroller, which is connected to both devices for identifying the voltages. The microcontroller can preferably be reset by a power supply unit in the household appliance. The microcontroller has inputs for checking control elements and sensors, as well as outputs for controlling actuators and control indications or operating displays. The microcontroller preferably has a non-volatile memory, in particular an EEPROM.
While an operating program is running, the data that reflects the program status that has in each case been reached is preferably stored cyclically in the memory.
In accordance with yet another feature of the invention, in the event of an interruption that is caused by an interruption switch, for example, a door-operated switch, by the user, for example, when a piece of laundry is subsequently inserted into a washing machine during the washing process, the running of the program can be continued once the interruption has ended.
In accordance with yet a further feature of the invention, there is provided an energy store for supplying electricity to the microcontroller after a power failure, the control apparatus being programmed to store the data relating to the given point in the program run in the memory after identification of a power failure.
In accordance with yet an added feature of the invention, there is provided an interruption switch, and a third identification device is associated with the interruption switch, the third identification device identifying a deliberate program interruption and producing an output signal and the control apparatus is programmed to decide, based upon the output signal of the third identification device, whether one of a failure and a change in an electrical variable of the appliance is due to a failure of the power supply system, to a deliberate switching off by the operator, or to a deliberate program interruption, to store, in the memory, the program status reached at a time when the program was interrupted, and once the program interruption has ended, to continue running the program from the stored program status.
With the objects of the invention in view, in a programmable household appliance configured to be switched off by an operator deliberately even while a program is running, there is also provided a power failure identification apparatus including a power supply, a mains switch supplying power to the appliance from an external electrical power supply system, the mains switch electrically connected to the power supply, an electronic program control apparatus electrically connected to the power supply and to the mains switch, the control apparatus having a memory for recording a program status of the appliance, a first means for identifying an electrical variable disposed between the mains switch and the external power supply system, a second means for identifying an electrical variable disposed between the mains switch and the appliance, the first and second identification means each identifying an electrical variable of at least one of the external power supply system and the power supply, and producing an output signal based upon the electrical variable, and the control apparatus programmed to store the program status if the external power supply system fails, to compare the output signal of each of the first and second identification devices, to determine whether one of a failure and a change in a respective electrical variable is due to a failure of the external power supply system or to the operator deliberately switching off the appliance, and to continue running the program from a point defined by the program status once the failure of the external power supply system has ended.
With the objects of the invention in view, there is also provided a method for identifying a power failure in a programmable household appliance configured to be switched off by an operator deliberately even while a program is running, including the steps of connecting a first identification device between the mains switch and the external power supply system and connecting a second identification device between the mains switch and the appliance, supplying power to the appliance through a mains switch from an external electrical power supply system, storing a program status in a memory of an electronic program control apparatus if the external power supply system fails, identifying one of an electrical variable of the power supply system and an electrical variable of the supply system in the appliance with the first and second identification devices and producing a respective output signal from the first and second identification devices, determining, with the control apparatus, whether one of a failure and a change of the electrical variable is due to a failure of the external power supply system or to a deliberate switching off of the appliance by the operator by comparing the signals produced by each of the first and second identification devices, and continuing the program from the stored program status once the failure of the power supply system has ended.
Other features that are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in an apparatus for power failure identification in a programmable household appliance, it is, nevertheless, not intended to be limited to the details shown because various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.